I'm hoping any ventilation issues would be resolved before the servers come fully online. I'd keep it safe and make both servers very well ventilated and not on top of each other like in the final picture you took a few posts back.

Rack-mounted servers are designed so that they suck cool air in front and exhaust warm air at the back. It is assumed that warm air will get removed somehow by AC. The worst thing is to create room for warm air to move to the front of rack where it mixes with 'fresh' cool air and thus increases temperature of input air. To avoid that one should install blank plates at the front of rack wherever rack is not occupied by equipment. In addition to that, machines ought to be stacked bottom-up so that warm air has opportunity to raise and escape from rack at the top.
If one leaves some space between two machines and follows rule about mounting blank plate at that space, air doesn't circulate in that narrow space between two machines, hence machines aren't cooled any better this way.

We have a rack of HP servers (mostly cousins of our Carolyn and Oscar - Proliants DL 360, 380, 580, 585 and ML 370) and storage enclosures (multiple MSA40 and MSA70) densely occupying 36 out of 42 U space whithout any problems with cooling. One Linux machine (this one) has continous uptime of 1612 days and ticking.

All those redundant ventilators in decent servers come with a reason. When these machines do what they are supposed to - and doing it real fast -, they sound like low-flying jet plane.Metod ...

If the exhaust air can't be directed to where it could be used to assist heating somewhere else, it should be vented outside to avoid loading the A/C.
Ideally this waste energy could be stored with a heat pump for reuase in the winter.

Your right about the servers....i have a hp proliant 585 server, and it doe sound like an aircraft when it starts up....its deafening....thats why its in my basement....out of sight, out of mind, and i cant hear it....lol

All very good ideas if you have the budget to have a specialized A/C for the server room.

Well, one thing is proper way of populating a server closet. Another thing is how to remove excess heat from it's surroundings. If you can not afford decent AC (it doesn't have to be specialized server room, could be plain home AC), then you can try to do your best, eg. by orienting closet in suitable way. Anyhow, you need to remove heat from surroundins of server closet and let closet and boxen inside to do their job (which includes moving air from one end to another).

But then, when it comes to budgetary woes: server closets don't come cheap, machines in rack mount chasis don't come cheap. If you consider all that, investment in modest AC is not that high after all.Metod ...

If the exhaust air can't be directed to where it could be used to assist heating somewhere else, it should be vented outside to avoid loading the A/C.
Ideally this waste energy could be stored with a heat pump for reuase in the winter.

Unfortunately the first suggestion won't work - there is no access to outside air from the Server Closet. (the "server closet" really is a (former utility) closet!) The heat pump idea would be viable, if someone could persuade the UC Berkeley administration that it would save lots of money that way...

The server closet has A/C, BTW! (the first breakdown in October was the A/C!).

If the exhaust air can't be directed to where it could be used to assist heating somewhere else, it should be vented outside to avoid loading the A/C.
Ideally this waste energy could be stored with a heat pump for reuase in the winter.

If you want to redirect exhaust air somewhere else, then you need to suck other air into server room. Which means dust unless you filter incoming air. Dust mostly means trouble as everybody knows. That's why most (if not all) server rooms use A/C to remove excessive heat.

Now, A/C is in principle heat pump. Owners are free to do whatever they think of with heat at the hot end of heat pump. Most owners don't think of anything and just let fans do their jobs.Metod ...

Let me add my thanks for your news posts, Matt. And, as has been said previously, we will be here waiting. Don't start the project up until you're satisfied that everything will run smoothly. Give Carolyn and Jocelyn our best! :-)

Yes, start it up when you are ready, but please start it slowly until you know better what it will handle. I'd rather see a few wu's occasionally, than have so many fits and starts like we have had since (well, forever).

If the exhaust air can't be directed to where it could be used to assist heating somewhere else, it should be vented outside to avoid loading the A/C.

I would have thought that Seti has a wealth of experience in getting rid of hot air! :-))) But I'm quite happy to let the guys set things up as they best see fit. Over the last year given all the trials and tribulations that they've had, they probably know more about setting up and admining servers, than a lot of people do.

They've made do with second-hand kit and donated pre-production stuff for many years, and although they were genuinely grateful for that, they now have the opportunity to start afresh with brand new state of the art equipment. It just makes so much sense to me to get it right and not rush things. Those are my principles, and if you don't like them ... well, I have others.
Groucho Marx 1895-1977

I also have mine, and if you don't like them ... tough, live with it.
Chris S 2016